The present invention relates to a gas stove burner. More particularly this invention concerns such a burner which is set up to form a small separate simmer flame.
A high-quality stove gas burner typically can produce a relatively large main flame and a smaller warming flame. The latter is normally set such that it cannot exceed a certain size, so that it can be used for simmering or warming but is not really powerful enough for most cooking procedures. The main flame is produced from nozzles that have an overall flow cross section that is much greater than the nozzles forming the warming flame. Typically the warming flame produces about 20% to 25% as much heat as the main flame.
In the system described in U.S. Pat. No. 5,277,576, the warming flame is centered in the burner and in this case it can be even smaller, between 10% and 12% of the overall burner capacity. While this is very handy for most applications, the centered position of this flame creates a hot spot in the center of the cooking utensil sitting on the burner, and in fact food can be burnt because of this concentrated location even in spite of the small size of the flame. Another disadvantage with this system is that a separate igniter must often be provided for the central flame, adding to the cost of the burner, and in general such a dual-flame burner can be quite complex.
It is therefore an object of the present invention to provide an improved gas burner for a cook stove.
Another object is the provision of such an improved gas burner for a cook stove which overcomes the above-given disadvantages, that is which has a full-size simmer flame.
A gas stove burner has according to the invention a base defining an axis and a ring assembly sitting on the base, forming therewith an annular outer compartment and a central inner compartment, and formed with an array of outwardly open lower passages open radially inward into the outer compartment. A generally imperforate cover disk overlying the ring assembly has an outer edge, upwardly closes the inner compartment, and forms with the ring assembly an array of upper passages open radially inward into the inner compartment and radially outward at the disk outer edge. Inlets on the base feed respective gas/air mixtures to the compartments and form a main flame at the edge from the mixture exiting the lower passages and a simmer flame at the edge from the mixture exiting the upper passages.
Thus with this system two different gas/air mixtures, one mixed for a large heating flame and the other for a small simmer flame, are fed to the burner and both create annular flames of generally the same diameter. The simmer flame is not a small point flame centered inside the main flame but instead is a large annular flame of the same size as the main flame. The provision of the jets for the simmer flame above those for the main flame eliminates the need for a second ignitor for the simmer flame, as when one moves to the simmer mode the main flame, which normally burns briefly as the simmer flame is started up, will serve to ignite it. What is more, when shifting back to use of the main flame, the residual gas of the simmer flame, even if same is extinguished, will be sucked up and consumed by the main flame.
According to the invention the ring assembly is formed by an upper ring and a lower ring centered on the axis and nested coaxially together. The cover disk can have a downwardly projecting annular ridge centered on the axis so that any spillage will not get into the burner. Furthermore this lip forms a downwardly open compartment that will be filled with the simmer-flame gas and make it less sensitive to drafts that might extinguish it.
In accordance with the invention the upper ring has an upwardly projecting annular ridge nested with the cover-disk ridge and the ridges together form an annular groove into which the lower passages open. One of the ridges is axially taller than the other of the ridges and supports the cover disk on the upper ring. This one tall ridge is formed with radially throughgoing notches forming the upper passages and is of triangular section so that it meets the other part in generally line contact, or as a series of circular line segments.
The cover disk according to the invention is of greater diameter than the ring assembly and the outer edge projects radially outwardly slightly past the ring assembly. Furthermore the outer compartment is annular and surrounds the inner compartment.